Waste water is transported through a system of pipes, known as sewers, from the point of generation to a remote treatment or disposal site. The sewers are usually buried anywhere from ten or more feet below the surface and access to the generally horizontal sewer sections is normally provided by a vertically disposed manhole. The manhole has an opening at the surface or grade level. The lower or invert end of the manhole has a flow path, known as a lateral, through which sewage flows on its way to the treatment plant. The manhole may be formed of cement, concrete or brick, and typically has an internal diameter many times greater than the diameter of the flow path of the lateral.
Sewage, as known to those skilled in the art, may generate an atmosphere which is damaging to the mortar with which the brick manhole is formed. Alternatively, the environment may be damaging to the cementitious material used in manufacturing the manhole. There is a need, therefore, to rehabilitate or repair the damaged manhole, both in order to maintain proper flow of sewage and to preserve the integrity of the sewage system during periods of heavy rainfall or subsurface water infiltration. Should the mortar be destroyed, then rainfall or surface water may enter the manhole, thereby overloading the sewage system and potentially causing untreated sewage to be discharged into streams, lakes, and the like. Preserving the structural integrity of the manhole is one means of minimizing the load applied to a sewage pumping treatment plant. These problems also apply to sewage stations which may be located along the sewage collection system, and which therefrom also require rehabilitation.